Robert Lewandowski scored twice in the first half either side of Alex Balde's back-post strike to set Barca on their way. Jules Kounde added a fourth after the break as Barca cruised to a win that put them 14 points clear of second-placed Real Madrid to clinch the title with four games to spare.
It is the 27th time the Blaugrana have won the Spanish top flight crown -- only Madrid have won it more times (35) -- and the first since Xavi Hernandez took charge at the end of 2021.
"It is a magnificent feeling, one of getting the job done well," Xavi said. "This started in July. It is 10 months of hard work and sacrifice. It felt like the moment tonight. There had been criticism about giving the players five days off which didn't sit well, but it served us well.
"The fans deserve this. The players, too. There has also been a titanic effort from the president to build a strong squad. Winning the title with four games left shows we have been much stronger than the rest [of the league], much stronger. It is a huge credit to the team.
"I am very happy, very proud to win the league title."
Barca won the league eight times between 2009 and 2019 as part of a golden era led by Lionel Messi but had failed to win it in the last three seasons.
Last year, the first without Messi following his move to Paris Saint-Germain, saw them end the campaign 13 points behind eventual winners Madrid.
However, that was viewed as a success given they were ninth when former midfielder Xavi replaced Ronald Koeman as coach at Spotify Camp Nou midway through the campaign.
After steadying the ship to lead Barca to Champions League qualification and a second-placed finish in the league, Barca backed Xavi in the transfer market last summer.
Lewandowski's goals have subsequently helped them regain their place at the top of Spanish football, with the Poland striker leading the league with 21 goals.
"The title gives the security to keep believing in this project. We have been brilliant in some games," Xavi added. "We want to win the four games left now and end the season well. The objective is achieved, though, winning LaLiga -- and also the Super Cup -- which is a massive achievement.
"We have suffered a lot. There is a lot of criticism here at this club. The work done is now valued enough. This is Barca and I know how it works. It was the same as a player."
They have kept 25 clean sheets in LaLiga this season, conceding just 13 goals -- and only two at Spotify Camp Nou -- recording 11 1-0 ways on the way to the title.
Results in Europe have been less convincing, with Barca exiting both the Champions League and the Europa League early, but there was a memorable Spanish Super Cup final win over Madrid, which brought the first trophy of the Xavi era.
Madrid gained revenge in the Copa del Rey semifinal, beating Barca 4-0 at Camp Nou after losing the first leg 1-0 at the Santiago Bernabeu. Los Blancos went on to beat Osasuna in the final.